In general, a rotary press means an apparatus which prints at high speed on printing materials such as newspaper, magazine and pamphlet.
FIGS. 6 through 8 are a schematic view showing a conventional rotary press, respectively. FIG. 6 is a schematic view showing a conventional double-side color printing rotary press for printing on newspaper at high speed, FIG. 7 is a schematic view showing a conventional commercial double-side color printing rotary press for printing at high speed on printing materials such as magazine and pamphlet, and FIG. 8 is a schematic view showing a conventional rotary press for one-side color printing on newspaper.
Referring to FIGS. 6 and 7, a conventional double-side color printing rotary press includes first and fourth printing units 1-4 which print different colored characters or figures on double sides of printing paper, respectively.
In each of the printing units 1-4, a pair of plate cylinders 5 and 6 are installed to oppose each other and a pair of blanket cylinders 7 and 8 are installed to oppose each other, in order to print on respectively different sides. Here, printing paper 9 passes through between the blanket cylinders 7 and 8 which oppose and contact each other.
In the case of the conventional rotary press having the above-described configuration, respectively different characters or figures are printed on the double sides of the printing paper 9 by the blanket cylinders 7 and 8 when the printing paper 9 passes through between the blanket cylinders 7 and 8 of each of the printing units 1-4.
That is, when printing paper 9 passes through the first printing unit 1, first colored characters or figures are printed on the double sides of the printing paper 9 by the blanket cylinders 7 and 8 in the first printing unit 1. When the printing paper 9 having passed through the first printing unit 1 passes through the second printing unit 2, second colored characters or figures are printed in the second printing unit 2. Thereafter, when the printing paper 9 passes through the third and fourth printing units 3 and 4, third and fourth colored characters or figures are respectively printed on the double sides of the printing paper 9.
Also, as shown in FIG. 8, blanket cylinders 7 and 8 and plate cylinders 5 and 6 for first-color printing on both sides of printing paper are formed in a first printing unit 1 of a one-side color printing rotary press. Also, a pair of cylinders having a blanket cylinder 7 and a plate cylinder 5 for printing second-color, third-color and fourth-color characters or figures in sequence, on one side of printing paper in second through fourth printing units 2 through 4 of the one-side color printing rotary press.
However, since printing paper passes through between blanket cylinders in a linear contacting manner when passing through each printing unit in the conventional rotary press, color pins are seceded due to moving of the printing paper at the time of changing in speed or tension of the printing paper to be fed, to thereby lower positional correctness of characters or figures of different colors which are printed on printing paper, and thus prevent accurate printing due to mismatched focus of contents to be finally printed, or occurring of pin secession.
In particular, printing paper for newspaper is severely expanded one thousands at maximum due to ink and moisture which are supplied during printing in a newspaper rotary press and thus a printing effect becomes further lowered.
Since even a one-side color printing rotary press also includes four printing units as in a double-side color printing rotary press, the structure of the one-side color printing rotary press becomes complicated unnecessarily. Since it is difficult to change structure of a one-side color printing rotary press into that of a double-side color printing rotary press, an additional double-side color printing rotary press should be purchased even at a state provided with a one-side color printing rotary press, to accordingly increase an economic load on users.